Pt. 36, App. G

14 CFR Ch. I (1-1-19 Edition)

made using the nominal value of k when
MT is larger than MR. The reference helical tip Mach number MR is the Mach
number corresponding to the reference
conditions (RPM, airspeed, temperature)
above the measurement point.
(4) Measured sound levels in decibels must
be corrected for engine power by algebraically adding an increment equal to

PART D - NOISE LIMITS

Delta (3) = K3 log (PR/PT)
where PR and PT are the test and reference
engine powers respectively obtained from
the manifold pressure/torque gauges and
engine rpm. The value of K3 shall be determined from approved data from the
test airplane. In the absence of flight
test data and at the discretion of the Administrator, a value of K3 = 17 may be
used.
Sec. G36.203 Validity of Results.

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(a) The measuring point must be overflown
at least six times. The test results must
produce an average noise level (LAmax) value
within a 90 percent confidence limit. The average noise level is the arithmetic average of
the corrected acoustical measurements for
all valid test runs over the measuring point.
(b) The samples must be large enough to
establish statistically a 90 percent confidence limit not exceeding Section1.5 dB(A). No
test results may be omitted from the averaging process unless omission is approved by
the FAA.

Sec. G36.301 Aircraft noise limits.
(a) Compliance with this section must be
shown with noise data measured and corrected as prescribed in Parts B and C of this
appendix.
(b) For single-engine airplanes for which
the original type certification application is
received before February 3, 2006 and multiengine airplanes, the noise level must not exceed 76 dB(A) up to and including aircraft
weights of 1,320 pounds (600 kg). For aircraft
weights greater than 1,320 pounds, the limit
increases from that point with the logarithm
of airplane weight at the rate of 9.83 dB (A)
per doubling of weight, until the limit of 88
dB (A) is reached, after which the limit is
constant up to and including 19,000 pounds
(8,618 kg). Figure G2 shows noise level limits
vs airplane weight.
(c) For single-engine airplanes for which
the original type certification application is
received on or after February 3, 2006, the
noise level must not exceed 70dB(A) for aircraft having a maximum certificated takeoff
weight of 1,257 pounds (570 kg) or less. For
aircraft weights greater than 1,257 pounds,
the noise limit increases from that point
with the logarithm of airplane weight at the
rate of 10.75dB(A) per doubling of weight,
until the limit of 85dB(A) is reached, after
which the limit is constant up to and including 19,000 pounds (8,618 kg). Figure G2 depicts
noise level limits for airplane weights for
single-engine airplanes.